I really don't know. I live in an extreme hills biome, i got a lot of emeralds (specially because I have fortune pickaxe), and I have got many of them from villagers as well... I have exactly 192 emeralds... I intend to use them as blocks for the beacon, since the others (gold/iron/diamond) are ACTUALLY useful. (I mean, you can use emerald to buy stuff, but it's not that useful when you are really ahead in the game... the only stuff worth buying are diamond tools/armor from the blacksmith).
Yes, that is a lot, 193 is a lot. I probably mined about 30 of them. The others I got mainly from the librarian (enchanted book/book/paper is really easy to get tons of) and a villager that bought wheat and raw chicken...
Well I have about 2 stacks because I live near extreme hills, and I have a fortune 3 pickaxe. Pretty beast
By 2 stacks, I mean I have 64 and 29 emeralds. Oh btw, I like emeralds, too. Thats why I have so many xD
I moved my mining operation to an Extreme Hills biome when I learned that emeralds are ONLY found there.
I use a Silk Touch enchantment on my diamond pickaxe. I don't mine emeralds, I mine the emerald ore and save them. When I need emerald, then I use a Fortune III enchanted pickaxe on the ore to get more emeralds than normal.
Within one week I had a full stack (64) of emerald ore. Using Fortune III will give me at least TWO full stacks of emeralds, if not more.
So yeah, I have a lot of emeralds now. But I spend a lot of my time mining.
I also have 3 full stacks of diamond ore now, which will turn into about 8-9 full stacks of diamonds when I use Fortune III pickaxe on them! Life is good!
The Meaning of Life, the Universe, and Everything.
I live in Extreme Hills, so I have some. Most of my local mining was done before I had any fortune picks, though, so I don't have a ton. Maybe 50 or so. (Edit: actually I have 85) I've yet to trade for any from villagers.